Vehicle electric power supply system

ABSTRACT

The present invention is vehicle electric power supply system (A) that supplies electric power wirelessly to a vehicle (M) that is positioned within an electric power supply area (X). The vehicle electric power supply system (A) has: a power-receiving device (m 1 ) that is provided in the vehicle; a plurality of power-transmitting devices ( 1   a   1, 1   a   2, 1   a   3, 1   b   1, 1   b   2, 1   b   3, 1   c   1, 1   c   2, 1   c   3 ) that are provided at mutually different positions within the electric power supply area; a position detecting device ( 4 ) that detects the position of the power-receiving device within the electric power supply area; and a control device ( 4 ) that, based on detection results from the position detecting device, selects from among the plurality of power-transmitting devices the power-transmitting device that is located in a position that corresponds to the power-receiving device, and then causes power to be supplied wirelessly from the selected power-transmitting device.

TECHNICAL FIELD

The present invention relates to a vehicle electric power supply system.Priority is claimed on Japanese Patent Application No. 2011-203318,filed Sep. 16, 2011, the contents of which are incorporated herein byreference.

TECHNICAL BACKGROUND

It is sometimes difficult for vehicles such as hybrid vehicles andelectric vehicles to travel long distances because of problems such asthe performance of the mounted batteries and the like. Because of this,in recent years, in addition to supplying electric power to suchbatteries at users' homes and the like, it has been proposed thatelectric power supply areas be provided in a variety of locations alongroutes traveled by vehicles such as, for example, road stops, gasstations, hill slopes, and intersections and the like. For example, inPatent document 1 a vehicle electric power supply system is disclosedthat supplies power wirelessly to a vehicle by utilizing trafficsignals.

DOCUMENTS OF THE PRIOR ART Patent Documents

-   [Patent document 1] Japanese Patent Application First Publication    No. 2010-193657

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

When electric power is being supplied wirelessly, the positionalrelationship between the power-receiving device provided in the vehicleand the power-transmitting device provided within the electric powersupply area affects the efficiency of the electric power supply. Forexample, in locations where the position of the vehicle is more or lessfixed, such as the parking space of a private home, there is no problemwith the electric power supply efficiency. However, as in theaforementioned conventional technology, when electric power is suppliedwirelessly while a vehicle is actually traveling, then it is easy forthe position of the vehicle within the electric power supply area to bearbitrarily decided depending on the will of the driver. Because ofthis, positional mismatching between the power-receiving device and thepower-transmitting device increases and this causes the electric powersupply efficiency to deteriorate. Moreover, in some cases, the positionwhere the power-receiving device is installed in the vehicle may differdepending on the type of vehicle, i.e., depending on whether the vehicleis a passenger vehicle or a truck or the like. Because of this,positional mismatching between the power-receiving device and thepower-transmitting device increases and cases such as this also causethe electric power supply efficiency to deteriorate.

The present invention was conceived in view of the above-describedproblems and it is an object thereof to provide a vehicle electric powersupply system that is able to suppress any deterioration in the electricpower supply efficiency.

Means for Solving the Problem

The present invention employs the following structure as a means ofsolving the above-described problems. A first aspect of the presentinvention is a vehicle electric power supply system that supplieselectric power wirelessly to a vehicle that is positioned within anelectric power supply area. This vehicle electric power supply systemhas a power-receiving device that is provided in the vehicle; aplurality of power-transmitting devices that are provided at mutuallydifferent positions within the electric power supply area; a positiondetecting device that detects the position of the power-receiving devicewithin the electric power supply area; and a control device that, basedon detection results from the position detecting device, selects fromamong the plurality of power-transmitting devices the power-transmittingdevice that is located in a position that corresponds to thepower-receiving device, and then causes power to be supplied wirelesslyfrom the selected power-transmitting device.

A second aspect of the present invention is the vehicle electric powersupply system according to the above-described first aspect in which,based on the detection results from the position detecting device, thecontrol device selects from among the plurality of power-transmittingdevices the power-transmitting device that is located in the closestposition to the power-receiving device, and then causes power to besupplied wirelessly from the selected power-transmitting device.

A third aspect of the present invention is the vehicle electric powersupply system according to the above-described first or second aspectsin which, when the position detecting device has detected the positionsof a plurality of the power-receiving devices within the electric powersupply area, then based on the detection results from the positiondetecting device, the control device selects from among the plurality ofpower-transmitting devices the respective power-transmitting devicesthat are placed in positions that correspond to each one of theplurality of power-receiving devices, and causes power to be suppliedwirelessly from the selected power-transmitting devices.

A fourth aspect of the present invention is the vehicle electric powersupply system according to any one of the above-described first throughthird aspects in which the power-transmitting devices are provided withpower-transmitting coils, and the power-receiving devices are providedwith power-receiving coils, and the power-transmitting devices transmitpower wirelessly by causing their power-transmitting coils to beelectromagnetically coupled with the power-receiving coils.

A fifth aspect of the present invention is the vehicle electric powersupply system according to the above-described fourth aspect in whichthe power-transmitting coils and the power-receiving coils are used asthe position detecting device.

Effects of the Invention

According to the present invention, a plurality of power-transmittingdevices are provided within an electric power supply area, and theposition of a power-receiving device provided in the vehicle within theelectric power supply area is detected. By doing this, it is possible toselect from the plurality of power-transmitting devices thepower-transmitting device that is located in the optimum position tosupply electric power wirelessly, and to supply electric power using theselected power-transmitting device. As a result, it is possible tosuppress any deterioration in the electric power supply efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system structure view showing the mechanism structure of avehicle electric power supply system according to an embodiment of thepresent invention.

FIG. 2 is a typical view showing an example of the layout of a vehicleelectric power supply system according to an embodiment of the presentinvention.

FIG. 3 is a system structure view showing the mechanism structure of avehicle electric power supply system according to another embodiment ofthe present invention.

BEST EMBODIMENTS FOR IMPLEMENTING THE INVENTION

Hereinafter, embodiments of the present invention will be described indetail with reference made to the drawings.

FIG. 1 is a system structure view showing the mechanism structure of avehicle electric power supply system A according to an embodiment of thepresent invention. As is shown in FIG. 1, this vehicle electric powersupply system A supplies electric power wirelessly to a vehicle M thatis positioned within an electric power supply area X. A plurality ofpower-transmitting coils (i.e., power-transmitting devices) 1 a 1, 1 a2, and 1 a 3 are provided within the electric power supply area X. Apower-receiving coil (i.e., a power-receiving device) m1 is provided inthe vehicle M.

The power-receiving coil m1 is provided in a bottom portion of thevehicle M such that the power-receiving coil will face towards thepower-transmitting coil 1 a 1 and the like. The power-receiving coil m1has substantially the same coil diameter as the power-transmitting coil1 a 1 and the like, and receives AC power wirelessly by beingelectromagnetically coupled to the power-transmitting coil 1 a 1 and thelike. In other words, the vehicle electric power supply system A is apower supply system in which power is supplied wirelessly to the vehicleM as a result of the power-transmitting coil 1 a 1 and the like beingelectromagnetically coupled to the power-receiving coil m1 of thevehicle M.

The supplying of power wirelessly from the power-transmitting coil 1 a 1and the like in the vehicle electric power supply system A to thepower-receiving coil m1 is performed based on magnetic resonance.Namely, a resonance capacitor (not shown) that forms part of a resonancecircuit is connected to both the power-transmitting coil 1 a 1 and thelike and the power-receiving coil m1. For example, the electrostaticcapacitance of the resonance capacitor is set such that the resonancefrequency of the resonance circuit on the power supply side, which isprovided with the power-transmitting coil 1 a 1 and the like and withthe resonance capacitor, be the same as the resonance frequency of theresonance circuit on the power receiving side, which is provided withthe power-receiving coil m1 and with the resonance capacitor.

In addition to the power-receiving coil m1, the vehicle M is providedwith a charging circuit m2, a battery m3, and a charging control unitm4. The power-receiving coil m1 outputs AC power (i.e. received power)that it has received from the power-transmitting coil 1 a 1 to thecharging circuit m2. The charging circuit m2 is a power conversioncircuit (i.e., a converter) that, based on charging control signals thatthe charging circuit m2 receives from the charging control unit m4,converts the received power into DC power that it then supplies to thebattery m3. Namely, based on the charging control signals, the chargingcircuit m2 charges the battery m3 by supplying charging current to thebattery m3 in accordance with the charged state of the battery m3.

The battery m3 is the source of drive power for the vehicle M. Thebattery m3 is a rechargeable battery that is capable of storingsufficient power and, for example, is a lithium-ion rechargeable batteryor a nickel-hydrogen rechargeable battery or the like. The battery m3 ischarged by the DC current supplied from the charging circuit m2, andalso supplies (i.e., discharges) traveling drive power to a drive powerconverter (not shown). The charging control unit m4 is a control devicethat controls the power conversion operations of the charging circuit m2and controls the charging of the battery m3. When the charging controlunit m4 detects, on the basis, for example, of changes in the voltagebetween the terminals of the power receiving coil m1, that thepower-receiving coil m1 has received AC power from the power-supply coil1 a 1 and the like, the charging control unit m4 causes the chargingcircuit m2 to operate so as to cause the battery m3 to be charged withDC power.

The power-transmitting coils 1 a 1, 1 a 2, and 1 a 3 are set inpositions that are mutually different from each other within theelectric power supply area X, which is a predetermined area that isestablished on the road surface along which the vehicle M travels. Morespecifically, the power-transmitting coils 1 a 1, 1 a 2, and 1 a 3 areplaced apart from each other in the vehicle transverse direction of thevehicle M. The power-transmitting coil 1 a 1 is placed in the center ofthe road surface, while the power-transmitting coils 1 a 2 and 1 a 3 areplaced on either side of the power-transmitting coil 1 a 1 and at adistance therefrom. The power-transmitting coils 1 a 1, 1 a 2, and 1 a 3are embedded in the road adjacent to the road surface. Note that thenumber and placement of the power-transmitting coils described above aremerely examples thereof, and the present invention is not limited tothese examples.

A power supply converter 3 a is a device that, based on control signalsthat the power supply converter 3 a receives from a control device 4(i.e., position detecting device, control device), supplies AC power tothe power-transmitting coil 1 a 1 and the like for thepower-transmitting coils to use when they supply power. Morespecifically, the power supply converter 3 a supplies power supply ACpower via a selector switch 2 a to any one of the power-transmittingcoils 1 a 1, 1 a 2, and 1 a 3. The power supply converter 3 a converts50 Hz or 60 Hz commercial power into AC power of a frequency that issuitable for supplying power to the vehicle M (for example, betweenseveral hundred Hz and several MHz), and then outputs this power to therespective power-transmitting coils 1 a 1 and the like.

The selector switch 2 a is a device that, based on control signals thatthe selector switch 2 a receives from the control device 4, switches thecircuit that is electrically connected to the power supply converter 3a. The selector switch 2 a is designed such that it can be electricallyconnected to any one of the power-transmitting coils 1 a 1, 1 a 2, and 1a 3. By providing the selector switch 2 a, it is not necessary toprovide a dedicated power supply converter 3 a for each one of thepower-transmitting coils 1 a 1, 1 a 2, and 1 a 3. As a consequence ofthis, it is possible to increase the functionality and the efficiency ofthe structural components and control system of the vehicle electricpower supply system A.

The control device 4 detects the position of the power-receiving coil m1within the electric power supply area X and, based on the results ofthese detections, selects from among the plurality of power-transmittingcoils 1 a 1, 1 a 2, and 1 a 3 the power-transmitting coil 1 a 1 that islocated in a position that corresponds to the power-receiving coil m1.The control device 4 then causes power to be supplied wirelessly fromthe selected power-transmitting coil 1 a 1. Namely, when the controldevice 4 detects a position signal for the power-receiving coil m1, thecontrol device 4 switches the selector switch 2 a such that thepower-transmitting coil 1 a 1 that is located in the optimum position tosupply power wirelessly is selected, and then causes AC power from thepower supply converter 3 a to be supplied to the selectedpower-transmitting coil 1 a 1. This control device 4 corresponds to theposition detecting device and control device of the vehicle electricpower supply system A.

The control device 4 uses the power-transmitting coil 1 a 1 and the likeand the power-receiving coil m1 as a position detecting device. Morespecifically, by diverting both the power-transmitting coil 1 a 1 andthe like and the power-receiving coil m1 for the purpose of performingsignal transmissions, wireless communication between the control device4 and the charging control unit m4 is made possible via thepower-transmitting coil 1 a 1 and the like and the power-receiving coilm1. Via this wireless communication, information relating to theposition of the power-receiving coil m1 that is installed in the vehicleM is transmitted and received between the control device 4 and thecharging control unit m4, and the position of the power-receiving coilm1 within the electric power supply area X is detected. In this case,the power-transmitting coil 1 a 1 and the like and the power-receivingcoil m1 function as an antenna for wireless communication, and thecontrol device 4 and the charging control unit m4 function ascommunication devices that employ this antenna. This wirelesscommunication can also be used to determine the stopped state of thevehicle M within a stopping area, or to verify before a power supplycommences whether or not it is necessary for power to actually besupplied, or to transmit and receive transaction fee informationrelating to the supplying of power.

The control device 4 may detect the position of the power-receiving coilm1 within the electric power supply area X based on the amount ofcharged power per unit time that is stored in the battery m3. Forexample, in order to seek the position of the power-receiving coil m1,the control device 4 switches the selector switch 2 a at a regularpredetermined interval so as to supply power sequentially to thepower-transmitting coils 1 a 1, 1 a 2, and 1 a 3. The charging controlunit m4 calculates the amount of charged power per unit time that hasbeen stored in the battery m3 within each of the aforementioned regularpredetermined intervals by monitoring the level of the power charge inthe battery m3, and then transmits information about thepower-transmitting coil having the greatest charging efficiency to thecontrol device 4. In the case of wireless power supply, the smaller thepositional mismatching with the power-receiving coil m1, the greater thepower supplying efficiency of the power-transmitting coil. Because ofthis, the control device 4 is able to detect the position of thepower-receiving coil m1 from the above-described information (namely,the information about the power-transmitting coil having the greatestpower supplying efficiency)

Based on the results of the detection of the position of thepower-receiving coil m1, the control device 4 selects from among theplurality of power-transmitting coils 1 a 1, 1 a 2, and 1 a 3 thepower-transmitting coil 1 a 1 that is located in a position thatcorresponds to the power-receiving coil m1, and causes power to besupplied wirelessly from this selected power-transmitting coil 1 a 1.More specifically, when the control device 4 acquires via wirelesscommunication with the charging control unit m4 information relating tothe position of the power-receiving coil m1 that is installed in thevehicle M, the control device 4 associates the position information forthe power-receiving coil m1 with the placement information for thepower-transmitting coil 1 a 1 and the like that has been stored in it inadvance, and then selects the power-transmitting coil (i.e., thepower-transmitting coil 1 a 1) that is located closest to thepower-receiving coil m1. Moreover, when the control device 4 hasacquired information relating to the position of the power-receivingcoil m1 based on the amount of charged power per unit time that has beenstored in the battery m3, then the control device 4 simply selects thepower-transmitting coil (i.e., the power-transmitting coil 1 a 1) thathas the greatest power supply efficiency.

FIG. 2 is a typical diagram showing an example of the layout of thevehicle electric power supply system A of an embodiment of the presentinvention. FIG. 2 shows a case in which the electric power supply area Xof this vehicle electric power supply system A is established, forexample, in a vehicle stopping bay on a road. This electric power supplyarea X is set to a size that enables a plurality of vehicles M to beable to stop therein (for example, to a size that enables threepassenger vehicles to stop therein), and such that any type of vehicle Mthat travels along the road is able to stop therein. For example, as isshown in FIG. 2, the position of the power-receiving coil m1 in theforemost vehicle M and the positions of the power-receiving coils m1 inthe vehicles M behind that vehicle are mutually different from eachother.

In addition to the power-transmitting coils 1 a 1, 1 a 2, and 1 a 3,power-transmitting coils 1 b 1, 1 b 2, and 1 b 3 and power-transmittingcoils 1 c 1, 1 c 2, and 1 c 3 are also provided in the electric powersupply area X. Note that the number and placement of thesepower-transmitting coils are merely examples thereof, and the presentinvention is not limited to these examples. For example, in the case ofan electric power supply area X that is formed in a road stopping bay,it is also possible for a plurality of power-transmitting coils to bearranged at predetermined spacings in a matrix layout. Moreover, aselector switch 2 b and a power supply converter 3 b that correspond tothe power-transmitting coils 1 b 1, 1 b 2, and 1 b 3, and a selectorswitch 2 c and a power supply converter 3 c that correspond to thepower-transmitting coils 1 c 1, 1 c 2, and 1 c 3 are each provided inthe electric power supply area X, and these are electrically connectedto the control device 4.

When the control device 4 has detected the positions of the plurality ofpower-receiving coils m1 within the electric power supply area X usingthe above-described position detecting device, then based on the resultsof this position detection, the control device 4 selects from among theplurality of power-transmitting coil 1 a 1 and the like the respectivepower-transmitting coils (namely, the power-transmitting coil 1 a 1, thepower-transmitting coil 1 b 3, and the power-transmitting coil 1 c 2 inFIG. 2) that are located in positions that correspond to each of theplurality of power-receiving coils m1, and then causes power to besupplied wirelessly from the selected power-transmitting coils. As aresult of this, power can be wirelessly supplied simultaneously to theplurality of vehicles M that are positioned within the electric powersupply area X.

An operating sequence of the vehicle electric power supply system Ahaving the above-described structure will be described below. In thevehicle electric power supply system A, the electric power supply area Xis set within a vehicle stopping bay on a road. Accordingly, because theposition where a vehicle M stops within the electric power supply area Xdepends on the driving action of the driver, these stopping positionsare not consistently the same. Moreover, because any type of vehicle Mthat is traveling along the road is able to stop in the electric powersupply area X, the positions of the power-receiving coils m1 in thevehicles M are different in each vehicle M.

The AC power that is transmitted wirelessly from the power-transmittingcoil 1 a 1 and the like to the power-receiving coil m1 is at its maximumwhen the power-receiving coil m1 is directly above and facing directlytowards the power-transmitting coil 1 a 1 and the like, namely, when thepower-receiving coil m1 and the power-transmitting coil 1 a 1 and thelike are at their closest to each other. However, because of thecircumstances described above, the power-receiving coil m1 cannot beexpected to be situated so as to face directly towards a predeterminedpower-transmitting coil 1 a 1 and the like. In other words, the relativepositions between a power-receiving coil m1 and a predeterminedpower-transmitting coil 1 a 1 or the like will not always be the samebecause of the inconsistent stopping positions of the vehicle M. Becauseof this, in the vehicle electric power supply system A, the plurality ofpower-transmitting coils 1 a 1 and the like are installed in mutuallydifferent positions within the electric power supply area X.

The control device 4 constantly monitors whether or not a vehicle M iswithin the electric power supply area X by attempting to communicatewirelessly with the charging control unit m4 via the power-receivingcoil m1 in the vehicle M using the power-transmitting coil 1 a 1 and thelike as an antenna. For example, if there is no communication connectionwith the charging control unit m4, the control device 4 determines thatno vehicle M has stopped within the electric power supply area X. Incontrast, if there is a communication connection with the chargingcontrol unit m4, the control device 4 determines that a vehicle M hasstopped within the electric power supply area X.

When the control device 4 has determined that a vehicle M has stoppedwithin the electric power supply area X, the control device 4 detectsthe position of the power-receiving coil m1 of the vehicle M. Morespecifically, information relating to the position of thepower-receiving coil m1 that is installed in the vehicle M istransmitted and received by means of wireless communication between thecontrol device 4 and the charging control unit m4 via thepower-transmitting coil 1 a 1 and the like and the power-receiving coilm1, so that the position of the power-receiving coil m1 within theelectric power supply area X is detected. Alternatively, the selectorswitch 2 a and the like is switched at regular predetermined intervalssuch that power is supplied sequentially to the power-transmitting coils1 a 1, 1 a 2, and 1 a 3, so that the position of the power-receivingcoil m1 within the electric power supply area X is detected based on theamount of charged power per unit time that is actually stored in thebattery m3.

Alternatively, it is also possible to detect the position of thepower-receiving coil m1 within the electric power supply area X usingboth of these methods. For example, in the case of the second vehicle Mshown in FIG. 2, information relating to the position of thepower-receiving coil m1 that is installed in the vehicle M istransmitted and received firstly by wireless communication, andapproximate position information for the power-receiving coil m1 (i.e.,information such as the fact that the power receiving coil m1 is locatedon the right side of the vehicle body) is exchanged. Next, the positionof the power-receiving coil m1 can be detected both accurately and in ashort time by comparing the power-transmitting coils 1 b 1 and 1 b 2that correspond to this position of the power receiving coil m1 with theamount of charged power per unit time that is stored in the battery m3.Namely, compared to the retrieval time when the position of thepower-receiving coil m1 is accurately detected by sequentially supplyingpower to the power-transmitting coils 1 b 1, 1 b 2, and 1 b 3 right fromthe start, the retrieval time can be shortened by initially narrowing aretrieval range down to a retrieval range that is estimated based onapproximate information for the power-receiving coil m1.

After the position of the power-receiving coil m1 within the electricpower supply area X has been detected, based on the results of thisdetection, the control device 4 selects from among the plurality ofpower-transmitting coils 1 a 1 and the like the power-transmitting coil1 a 1 or the like that is located at a position that corresponds to thepower-receiving coil m1, and then causes power to be supplied wirelesslyfrom the selected power-transmitting coil 1 a 1 and the like. Forexample, if the control device 4 has detected that the power-receivingcoil m1 of the foremost vehicle M shown in FIG. 2 is positioned above ornearly above the power-transmitting coil 1 a 1, the control device 4selects this power-transmitting coil 1 a 1 and, by then switching theselector switch 2 a, the control device 4 causes power to be suppliedfrom the power supply converter 3 a to the power-transmitting coil 1 a1.

The power-receiving coil m1 of the vehicle M is electromagneticallycoupled to the power-transmitting coil 1 a 1. As a result of this, theAC power that is supplied from each power supply converter 3 a to thepower-transmitting coil 1 a 1 is wirelessly transmitted from thepower-transmitting coil 1 a 1 to the power-receiving coil m1 of thevehicle M. In the vehicle electric power supply system A, magneticresonance is used. Because of this, the transmission efficiency of theAC power that is wirelessly transmitted from the power-transmitting coil1 a 1 and the like to the power-receiving coil m1 is high.

During the period in which the control device 4 is connected forcommunication with the charging control unit m4, the control device 4continues the wireless power supply to the vehicle M via thepower-transmitting coil 1 a 1. When the connection for communicationbetween the control device 4 and the charging control unit m4 is brokenoff, the control device 4 determines that the vehicle M has moved out ofthe electric power supply area X and causes the supplying of power tothe power-transmitting coil 1 a 1 to cease. Thereafter, the controldevice 4 returns to its initial standby state, and monitors whether ornot a vehicle M stops within the electric power supply area X.

According to the above-described present embodiment, it is possible tosupply power wirelessly for a predetermined time to a vehicle M that hasstopped within a stopping bay on a road where an electric power supplyarea X has been established by utilizing the fact that the vehicle M isstopped. Accordingly, according to the present embodiment, it ispossible to supply power to the vehicle M at a particular locationpartway through the journey of the vehicle M. Namely, it is possible toboth encourage the public acceptance of a vehicle M which uses electricpower as a travel power source and improve the convenience of thevehicle M.

Moreover, according to the above-described present embodiment, thevehicle electric power supply system A that supplies power wirelessly toa vehicle M that is positioned within the electric power supply area Xhas a power-receiving coil m1 that is provided in the vehicle M, aplurality of power-transmitting coils 1 a 1 and the like that areprovided at mutually different positions within the electric powersupply area X, and a control device 4 that is equipped with a positiondetecting device that detects the position of the power-receiving coilm1 within the power supply area X, and with a control unit that, basedon detection results from this position detecting device, selects fromamong the plurality of power-transmitting coils 1 a 1 and the like thepower-transmitting coil 1 a 1 or the like that is located in a positionthat corresponds to the power-receiving coil m1, and then causes powerto be supplied wirelessly from the selected power-transmitting coil 1 a1. As a consequence, it is possible to select from among the pluralityof power-transmitting coils 1 a 1 and the like the power-transmittingcoil 1 a 1 or the like that is located in the optimum position forsupplying power wirelessly, and to then cause this power-transmittingcoil 1 a 1 or the like to supply power. Accordingly, in the presentembodiment, it is possible to achieve a vehicle electric power supplysystem A that is able to limit any reduction in the power supplyefficiency even when a vehicle M is supplied with power wirelesslypartway through its journey.

Note that the present invention is not limited to the above-describedrespective embodiments and, for example, the following variant examplesmay also be considered.

(1) In the present embodiment, as is shown in FIG. 2, thepower-transmitting coils 1 a 1 and the like, 1 b 1 and the like, and 1 c1 and the like that are located within the power supply area X areembedded in the road at a predetermined distance from each other.However, the present invention is not limited to this. For example, thestopping positions of the vehicles M change depending on the respectivesizes (i.e., vehicle lengths) of the foremost vehicle M and the vehiclesM to the rear of that vehicle. Because of this, it is also possible forthe power-transmitting coils 1 a 1 and the like of the rearward vehiclesM to be embedded in the road surface, for example, at the same distancefrom each other as the length of the vehicle M having the shortestvehicle length. Furthermore, it is also possible to provide the selectorswitches 2 a and the like and the power supply converters 3 a and thelike at the same distances from each other respectively as the length ofthat shortest vehicle M, and to supply power wirelessly at intervals ofthis vehicle length. If the power-transmitting coils 1 a 1 and the like,1 b 1 and the like, and 1 c 1 and the like are embedded at thesecomparatively short intervals, then even if a plurality of vehicles Mhaving mutually different sizes (i.e., vehicle lengths) stop within thepower supply area X, it is still possible for power to be supplied toeach of these vehicles M. Note that the number of power-transmittingcoils 1 a 1 and the like within the power supply area X is appropriatelyset in accordance with the location and environment and the like wherethe power supply area X is established.(2) In the present embodiment, the power-transmitting coils 1 a 1 andthe like are embedded in the road surface and the power-receiving coilsm1 are provided in a base portion of the vehicles M, and thepower-transmitting coils 1 a 1 and the like and the power-receivingcoils m1 are placed opposite each other in a vertical direction.However, the present invention is not limited to this. For example, itis also possible for the power-receiving coil m1 to be provided in aside portion (i.e., in an entrance door) of the vehicle M, and for thepower-transmitting coil 1 a 1 and the like to be provided on theshoulder of the road such that its center axis is horizontal and is alsoorthogonal to the axis of the traffic lane, and such that it faces theside portion (i.e., the entrance door) of the vehicle M. Moreover, it isalso possible for the power-receiving coil m1 to be provided in the roofportion of the vehicle M and for the power-transmitting coil 1 a 1 andthe like to be provided above the road so as to face the roof portion ofthe vehicle M.(3) In the present embodiment, as is shown in FIG. 1, the power supplyconverter 3 a supplies the AC power for the power supply to any one ofthe power-transmitting coils 1 a 1, 1 a 2, and 1 a 3 via the selectorswitch 2 a. However, the present invention is not limited to this. Forexample, as is shown in FIG. 3, it is also possible for independentpower supply converters 3 a 1, 3 a 2, and 3 a 3 to be directly connectedto the respective power-transmitting coils 1 a 1, 1 a 2, and 1 a 3, andfor the 50 Hz or 60 Hz commercial power that is supplied to each ofthese power supply converters to be switched by the selector switch 2 a.(4) In the present embodiment, the power-transmitting coils 1 a 1 andthe like and the power-receiving coils m1 are used as the positiondetecting device. However, the present invention is not limited to this.For example, instead of this, it is also possible for the vehicleelectric power supply system A (i.e., the on-ground facility) and thevehicle M to be furnished with their own separate communicationfunctions. For example, the use of known optical beacons or wirelesscommunication instruments that employ radio waves and the like for theseparate communication functions may also be considered. However,because it is only necessary for communication between the vehicleelectric power supply system A (i.e., the on-ground facility) and thevehicle M, in other words, for communication over a comparatively shortdistance to be possible, it is also possible to employ individuallydesigned communication systems for the separate communication functions.Moreover, it is also possible to design a system in which the stoppingposition and stopped state (i.e., attitude) of the vehicle M aredetected by measuring the latitude and longitude of the vehicle M viaGPS, or by embedding strain gauges in the road and then measuring theload thereon, or by measuring distance using a 3-D laser radar, and inwhich the position of the power-receiving coil m1 is then detected basedon the results from such detections.(5) In the present embodiment, the position of the power-receiving coilm1 within the electric power supply area X is detected based on wirelesscommunication between the control device 4 and the charging control unitm4 via the power-transmitting coils 1 a 1 and the like and thepower-receiving coil m1, or based on the amount of charged power perunit time that has accumulated in the battery m3, however, the presentinvention is not limited to this. For example, it is also possible tomount the power-receiving coil m1 in a predetermined position in thevehicle M (for example, in the position of the driver's seat in thefront-rear direction, and in the position of the center of the vehiclein the left right direction), and to install 3-D laser radar or a stereocamera in a position that enables it to photograph the entire electricpower supply area X (for example, in a position where it looks downdiagonally from above over the electric power supply area X). By doingthis, it is possible to detect the position of the vehicle from thephotographed images by means of three-dimensional shape matching, and tothereby indirectly determine the position of the power-receiving coilm1.(6) In the present embodiment, the electric power supply area X isestablished in a vehicle stopping bay on a road. However, the presentinvention is not limited to this. In addition to a road stopping bay,the various locations where the electric power supply area X can beestablished include, for example, areas in front of traffic signals thatare located on roads (i.e., public roads), areas in front of railwaylevel crossings, carparks in shopping centers, drive-through lanes instores and the like, and stopping areas in gas stations and the like.Moreover, the present invention is not limited to public roads andprivate roads and the like, and the electric power supply area X mayalso be established on private land such as home carparks and the like.(7) In the present embodiment, power is supplied wirelessly to a vehicleM (i.e., to a stopped vehicle) that is positioned within the electricpower supply area X without any preconditions being set. However, thepresent invention is not limited to this. For example, it is alsopossible to divert the power-transmitting coils 1 a 1 and the like andthe power-receiving coils m1 for the purpose of performing signaltransmissions so as to make wireless communication between the controldevice 4 and the charging control unit m4 possible, or to use thiswireless communication to verify the necessity of supplying power beforethe supplying of power commences, or to transmit and receive transactionfee information relating to the supplying of power. In this case, thepower-transmitting coils 1 a 1 and the like and the power-receivingcoils m1 function as an antenna for this wireless communication, and thecontrol device 4 and the charging control unit m4 function ascommunication devices that utilize this antenna. Moreover, it is notnecessary to divert the power-transmitting coils 1 a 1 and the like andthe power-receiving coils m1 for the purpose of performing signaltransmissions, but it is possible to perform wireless communicationusing separately provided individual communication devices.(8) In the present embodiment, a case is described in which the powerthat is supplied to the vehicle M is used to charge the battery m3.However, the present invention is not limited to this. For example, itis also possible for the power that is supplied to the vehicle M to beused to drive illumination devices or air-conditioning devices insidethe vehicle M.

INDUSTRIAL APPLICABILITY

According to the present invention, a plurality of electric powersupplying devices are provided within an electric power supply area, andthe position of a power-receiving device provided in a vehicle withinthe electric power supply area is detected. By doing this, it ispossible to select from the plurality of power-transmitting devices thepower-transmitting device that is located in the optimum position tosupply electric power wirelessly, and to supply electric power using theselected power-transmitting device. As a result, it is possible tosuppress any deterioration in the electric power supply efficiency.

DESCRIPTION OF THE REFERENCE NUMERALS

A . . . Vehicle electric power supply system, M . . . Vehicle, m1 . . .Power-receiving coil (Power-receiving device), X . . . Electric powersupply area, 1 a 1, 1 a 2, 1 a 3, 1 b 1, 1 b 2, 1 b 3, 1 c 1, 1 c 2, 1 c3 . . . Power-transmitting coils (Power-transmitting devices), 4 . . .Control device (Position detecting device, Control device)

What is claimed is:
 1. A vehicle electric power supply system thatsupplies electric power wirelessly to a vehicle that is positionedwithin an electric power supply area, comprising: a power-receivingdevice that is provided in the vehicle; a plurality ofpower-transmitting devices that are provided at mutually differentpositions within the electric power supply area; a position detectingdevice that detects the position of the power-receiving device withinthe electric power supply area; and a control device that, based ondetection results from the position detecting device, selects from amongthe plurality of power-transmitting devices the power-transmittingdevice that is located in a position that corresponds to thepower-receiving device, and then causes power to be supplied wirelesslyfrom the selected power-transmitting device.
 2. The vehicle electricpower supply system according to claim 1, wherein, based on thedetection results from the position detecting device, the control deviceselects from among the plurality of power-transmitting devices thepower-transmitting device that is located in the closest position to thepower-receiving device, and then causes power to be supplied wirelesslyfrom the selected power-transmitting device.
 3. The vehicle electricpower supply system according to claim 1, wherein, when the positiondetecting device has detected the positions of a plurality of thepower-receiving devices within the electric power supply area, thenbased on the detection results from the position detecting device, thecontrol device selects from among the plurality of power-transmittingdevices the respective power-transmitting devices that are placed inpositions that correspond to each one of the plurality ofpower-receiving devices, and causes power to be supplied wirelessly fromthe selected power-transmitting devices.
 4. The vehicle electric powersupply system according to claim 2, wherein, when the position detectingdevice has detected the positions of a plurality of the power-receivingdevices within the electric power supply area, then based on thedetection results from the position detecting device, the control deviceselects from among the plurality of power-transmitting devices therespective power-transmitting devices that are placed in positions thatcorrespond to each one of the plurality of power-receiving devices, andcauses power to be supplied wirelessly from the selectedpower-transmitting devices.
 5. The vehicle electric power supply systemaccording to claim 1, wherein the power-transmitting devices areprovided with power-transmitting coils, and the power-receiving devicesare provided with power-receiving coils, and the power-transmittingdevices transmit power wirelessly by causing their power-transmittingcoils to be electromagnetically coupled with the power-receiving coils.6. The vehicle electric power supply system according to claim 2,wherein the power-transmitting devices are provided withpower-transmitting coils, and the power-receiving devices are providedwith power-receiving coils, and the power-transmitting devices transmitpower wirelessly by causing their power-transmitting coils to beelectromagnetically coupled with the power-receiving coils.
 7. Thevehicle electric power supply system according to claim 3, wherein thepower-transmitting devices are provided with power-transmitting coils,and the power-receiving devices are provided with power-receiving coils,and the power-transmitting devices transmit power wirelessly by causingtheir power-transmitting coils to be electromagnetically coupled withthe power-receiving coils.
 8. The vehicle electric power supply systemaccording to claim 4, wherein the power-transmitting devices areprovided with power-transmitting coils, and the power-receiving devicesare provided with power-receiving coils, and the power-transmittingdevices transmit power wirelessly by causing their power-transmittingcoils to be electromagnetically coupled with the power-receiving coils.9. The vehicle electric power supply system according to claim 5,wherein the power-transmitting coils and the power-receiving coils areused as the position detecting device.
 10. The vehicle electric powersupply system according to claim 6, wherein the power-transmitting coilsand the power-receiving coils are used as the position detecting device.11. The vehicle electric power supply system according to claim 7,wherein the power-transmitting coils and the power-receiving coils areused as the position detecting device.
 12. The vehicle electric powersupply system according to claim 8, wherein the power-transmitting coilsand the power-receiving coils are used as the position detecting device.